Long Term Evolution (LTE) is a 4G wireless standard that provides superior performance in throughput and latency to previous generations of mobile wireless cellular standards. In addition, LTE compared to SATCOM mobile internet protocol (IP) connectivity is around an order of magnitude less expensive than the SATCOM IP service.
Providing air to ground (aircraft to ground) IP based connectivity over land masses using LTE poses a number of technical challenges, one of which is uplink synchronization, which is achieved via the random access channel (RACH). The RACH is designed for ground to ground communication, so is range limited in terms of round trip time (RTT) delay to about 100 km. It is envisioned that LTE cells for air to ground could be as large as 150 km to 200 km because of the more favorable line of sight (LOS) conditions.
Thus, a solution to uplink transmission timing is needed for air to ground (ATG) to function with realistic cell diameters.